The iPhone 5s' 8-MP camera takes photos with great color accuracy and sharpness, but it only captures half the detail of the Galaxy S5's 16-MP shooter. But it's not all about megapixels. The Galaxy S5 has real-time HDR (high-dynamic range), which uses different exposure levels for different parts of an image, while the iPhone can only provide this functionality on individual shots, not on videos or in preview mode.
The Galaxy S5 allows you to refocus your images after capturing them so you can focus on that face in the background rather than on the person in front. Add in previous Samsung features like Eraser Mode, which removes photobombers, and Best Face, which helps you pick the best smile for each person in a group photo, and you have a photography experience that's generations ahead of Apple's.